When two little girls briefly vanished from their father's Polk County home last week, electronic messages called Amber Alerts were fired off across the state within minutes.

Alerts popped up on highway message boards and to more than 30,000 e-mail boxes before the suspected abductors -- the girls' mother and her boyfriend -- were arrested in Orlando and the girls were found safe.

Getting such messages out as quickly as possible is considered key in helping law enforcement find missing people. And today's near-instantaneous alerts are a dramatic improvement over the way the public used to be notified about missing children.

Long before Amber Alerts, the faces of America's vanished children stared out from milk cartons during a short-lived initiative that provided long-term results for the nation's missing-children's movement.

In the mid-1980s, a Michigan-based nonprofit, the National Child Safety Council, spearheaded the national milk-carton initiative, publicizing photos of missing and endangered youth at a time when few such programs existed.

"What it did most was build awareness worldwide," said Barbara Huggett, director of research for the nonprofit. "Mexico, Canada, France -- it's not just a U.S. thing; it's known all over the world."

The nonprofit's founder, H.R. Wilkinson, was inspired by a small Iowa dairy that was putting missing children's photos on milk cartons. Wilkinson's nonprofit expanded the program, eventually enlisting more than 700 dairies across the country.

As many as 70 missing children were featured during the program's brief run. Of those, only one child was found alive, Huggett said.

Exactly why the effort ended after just a couple of years is not clear, though packaging was probably a factor, with plastic containers overtaking waxed-cardboard cartons in popularity.

Other issues, including financial constraints and the emergence of national missing-children programs, were likely other factors.

"The milk-cartons program ran its course," said Gaylord Walker, vice president of the National Child Safety Council. "They had a tremendous impact and they did a great job of creating public awareness."

That, it seems, may be its legacy.

The milk-carton initiative -- while still used in countries outside the U.S. -- remains an American icon of sorts, easily recognized even by today's youth.

"It's just engrained itself" in American culture, said Huggett, adding that the topic still comes up today in cartoons and jokes. The milk-carton initiative even inspired Halloween costumes. "It kind of cracks me up that it's come to that," she said.

But the effort also raised a serious issue in the public consciousness: the problem of missing children and the need for a national source of timely information, a service provided today by the National Center for Missing and Exploited Children in Virginia.

The center also helps with Amber Alerts -- a program named after a 9-year-old Texas girl who was abducted and murdered in 1996 -- to cell phones and emails.

"The technology makes it that much more immediate," said Nancy McBride, the center's national safety director.

As of Monday, Florida had six unsolved Amber Alerts for missing children, including Haleigh Cummings of Putnam County in 2009 and Trenton Duckett, who disappeared from Leesburg in 2006.

In 2008, 10 children were found after Florida Amber Alerts were issued, according to the Florida Department of Law Enforcement.